1. Field of the Invention
The present invention is concerned with improved film-forming skin protectant compositions capable of forming an elastic film when applied to skin and including a film-forming component dispersed in a carrier, and wherein the compositions of the invention are improved by provision of a quantity of nitrocellulose dispersed in the carrier; the nitrocellulose serves to create a more long-lasting film capable of protecting skin (e.g., the skin of bovine teats) over relatively long periods of time. More particularly, the preferred forms of the invention pertain to film-forming compositions including therein effective amounts of polyether polyurethane and benzoin gum dispersed in tetrahydrafuran (THF) solvent, with a minor amount of nitrocellulose therein.
2. Description of the Prior Art
A significant problem for dairy farmers is the incidence of mastitis in cattle. It is known that up to 40-50% of inflammatory infections are contracted to a cow's dry or non-lactating period, with the greatest percentages of these infections occurring the first and last two weeks of the dry period. At these times, the mammary gland is in the transitional state where immunological factors are preoccupied or suppressed, milk is no longer being flushed from the gland, and increased mammary pressure distends the teat, thus allowing for easier bacterial penetration through the milk canal.
It is known to apply protective compositions to bovine teats, especially during or leading up to the non-lactating period, in order to minimize the occurrence of mastitis. The primary goal in such mastitis treatment is to minimize bacterial exposure on the teat ends.
U.S. Pat. No. 5,192,536 describes protectant compositions containing polyether polyurethane dissolved in tetrahydrafuran. The compositions of this patent can be applied to animal skin to form a rapidly drying, elastic film having protectant qualities. U.S. Pat. No. 5,688,498 describes further compositions of this general character, but which are improved by the provision of benzoin gum (benzoin resinoid). It has been found that the benzoin gum significantly increases the adhesion time of the protectant compositions and renders the compositions suitable for dipping so as to improve the coverage of the compositions and for ease of use.
Pending application for U.S. Letters Patent Ser. No. 08/644,009, filed Feb. 14, 1997 is related to the '498 patent and describes further compositions making use of a variety of different solvents and additional ingredients such as germicides, dyes and optional ingredients, e.g., fillers, moisturizers, perfumes, and viscosity modifiers.
In addition to mastitis control, skin-protectant compositions also find utility as wound dressings to be applied to open wounds to protect against infection from dirt, insects or other sources of bacteria.
In order to enhance the protectiveness of skin protectant compositions of the forgoing types, it is desirable that it should remain intact on skin for as long as possible. This not only provides an added measure of protection against infection, but also lessens the time and expense involved in repeated reapplications of the compositions.
There is accordingly a need in the art for improved skin-protectant compositions which maintain the ease of use and protection capabilities of the known polyether polyurethane/benzoin gum compositions while giving increased wear integrity and longevity.